High altitude compensation of two position exhaust nozzle control



lUnited taes HIGH ALTITUDE COMPENSATION OF TWO POSI- TION EXHAUST NOZZLE CONTRL Charles H. Culbertson, Baltimore, Md., assigner, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Application .lune 21, 1955, Serial No. 517,108

2 Claims. (Cl. 60-35.6)

exhaust nozzle area under ordinary operating conditions,

considerable dilculty has been experienced heretofore in providing automatic control thereof when a primary electrical power failure of the propulsion unit occurs.

It is a principal object of the present invention to provide novel and improved apparatus for automatically posi- 3 tioning the exhaust area of a jet propulsion unit under emergency conditions.

It is a further object of the present invention to provide novel and improved emergency control apparatus for a jet propulsion unit whereby the effective exhaust area of the unit is determined by and controlled in accordance with the instantaneous deposition of its power lever or throttle and/or the altitude position of the aircraft.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

The single gure is a diagrammatic showing a preferred embodiment of the present invention.

ln general the improved emergency control apparatus of the present invention includes an emergency electrical power circuit, means responsive to energization of the circuit for operating a pair of exhaust nozzle closure segments toward their full open position when the power throttle of the unit is in its below military or its afterburner position, and means responsive to 'energization of the emergency power circuit and dependent upon the instantaneous altitude of the aircraft for operating the nozzle segments toward their full closed position when the throttle is in its military position. It has been found y that the above apparatus automatically satisfies the requirements of an emergency power failure situation or the like in a reliable and effective way.

A preferred embodiment of the present invention is shown in the drawing. As shown therein, iiuid from the liuid reservoir 3 is directed through conduit 4 successively through the pump 5, the relief valve 6, and the shut-oit valve 7 to the fluid inlet connection 8 of the control mechanism 9. The drain connection 10 for the control mechanism as well as the conduit 11, which is connected to the relief valve 6, are returned to the uid reservoir 3 through conduit 12. The outlet conduits 13 and 14 of the control mechanism 9 are connected to the actua- 'tor mechanism 15 on opposite sides of its piston 16 which is coupled through a suitable mechanical linkage syslem 16a to the pivotally mounted nozzle segments 17 and 2,834,182 Patented May 13, 1958 18 that control the effective area of the exhaust nozzle of the propulsion unit.

Since the control mechanism 9 may take a great variety of different forms, and since the details thereof form no part of the present invention, a full description of the same is not provided for the sake of simplicity. It need only be understood for the purposes of the present invention that under normal operating conditions the control mechanism controls the position of piston 16 in the actuator in accordance with a function of any suitable variable of the jet propulsion system such as its exhaust temperature or the like.

Fluid from the pump 5 and the relief valve 6 is also delivered through the conduit 19 to the inlet connection of the emergency valve assembly 20, and returns to the' iiuid reservoir 3 through its drain connections 21 and 22 and conduit 12. Conduits 23 and 24, which are respectively connected to the chambers a and 20b defined by the piston sections of the movable valve element 25 in the valve assembly, are connected to conduits 13 and 11tand chambers 15a and 15b of the actuator 15.' The coil spring elements or the like 20c and 20d preferably normally centrally position the valve element 25 within its cylinder or casing 20e.

The primary electrical circuit of the propulsion unit extends from the primary power source 26 through the `upper normally closed contact of the emergency switch 27 through the energizing coil 7aof the shut-off valve 7 to ground. in this way, as will be more apparent hereinafter, so long as the primary power source is intact and switch 27 is closed as indicated by lamp 28 the shut-off valve 7 will be maintained in its open position and the control mechanism will maintain the nozzle segments 17 and 18 in proper adjustment.

The power lever or throttle 29 of the jet propulsion unit is connected in any suitable manner to the cam element 30, which includes a raised portion that causes the switch 31 to move from a position where its lower contact is closed to a position where its upper contact is-closed when the throttle 29 moves through its military position.

One emergency power circuit of the propulsion unit extends from the emergency power source 32 through the lower contact of switch 27, contact 31a of switch 31 and winding 33 of solenoid 34 that is wound about the projection 35 of the valve element 25 of valve assembly v20. Another emergency power circuit for the propulsion unit extends from the emergency power source 32 through the lower contact of switch 27, contact 31b of switch 31, contact 36a of switch 36 and winding 37 of the solenoid to ground.

The position of switch 36 is controlled by the cam element 38 that is coupled to the nozzle segments 17 and 1S by means of the linkage system 16a. Cam element 38 is preferably step-shaped as shown such that as it moves from left to right switch 36 successively engages switch positions 36a, 36b and 36C. In this way as will be more apparent hereinafter, when switch 36 occupies its intermediate position 36b, the altitude pressure switch 39 is placed in series with the emergency power circuit.

in operation as indicated heretofore under normal operating conditions iiuid from the reservoir 3 and the pump 5 is directed through the shut-od valve 7, which is main'- tained in its open position so long as the primary power source remains intact, and through the control mechanism 9 to determine the position of piston 16 in actuator 15 and thereby properly adjust the position of the nozzle segments 17 and 18 of the propulsion unit. When the primary electrical system fails, the signal light or the like 28 will provide a suitable indication and deenergization of winding 7a will close shut-ott valve 7. When the pilot or operator of the propulsion unit depresses emergency switch 27 to energize indicator lamp 32a energizatiou of the solenoid 34 of the valve assembly 20 is controlled and determined by the instantaneous positions of the throttle 29, the nozzle segments 17 and 18, and their associated cam elements 30 and 38. Thus, if the throttle 29 occupies either its below military or afterburner position when the emergency switch 27 is closed, current will How through contact 31a of switch 31 to energize winding 33 of solenoid 34. This will cause the valve element 25 to move to the right and allow liuid at high pressure to flow from conduit 19 through chamber 20a and through conduits 23 and 14 into chamber 15b of actuator 15 thereby moving its piston 16 to the left and causing the nozzle segments 17 and 18 toy move to their full open position.

If the throttle 29 is in its military position when the emergency switch 27 is closed, current fiows though the upper contact 31h of switch 31 and the lower contact 36a of switch 36 to winding 37 of solenoid 34. This causes the valve element to move to the left and allow fluid to ow from conduit 19 through chamber 2Gb of the valve assembly and through conduits 24 and 13 into chamber 15a of the actuator device 15 thereby moving piston 16 to the right towards its full closed position. When switch 36 is moved to its intermediate position 36b by the hot day step in cam element 38 which limits flow of fuel through the main throttle valve to the combustion chamber when the temperature of the surrounding atmosphere exceeds 100 C. at sea level and which moves to the right as the nozzle segments close, the emergency electrical circuit is deenergized if the aircraft is near sea level and pressure switch 39 is open. Thus, the nozzle segments 17 and 18 will stop and lock in a predetermined partially closed position which is safe for operation of the aircraft at that altitude.

If, however, the aircraft is flying at or above its critical altitude, pressure switch 39 is closed and movement of the nozzle segments 17 and 18 will not be halted until the high altitude step in cam element 38 operates switch 36 to its uppermost open position 36C. In this way when the aircraft flies at a relatively high altitude, the nozzle segments may be positioned to provide improved ying performance without a material decreased margin of safety.

it is to be understood that use of the term throttle or power throttle" in the specification and claims of the present application refers to the actuating mechanism or lever which controls the fuel flow regulator between the fuel supply source and the combustion chamber of the jet propulsion unit, Use ofthe term military position of the throttle refers to that position of the lever which permits a maximum output thrust from the propulsion unit when the afterburner is not in operation, and

use of the term below military position of the throttlev refers to a position of the lever which provides less than the maximum thrust output of the engine, also when the afterburner is not operative. The afterburner position of the throttle refers to a position of the lever at which aftcrburning in addition to a maximum thrust output of the basic engine is provided.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. Emergency control apparatus for the variable exhaust nozzle of a jet propulsion unit said apparatus comprising a pressurized fluid Source; a fluid operated actuator which, when moved in one direction, increases the effective area of the exhaust nozzle and which, when moved in the opposite direction, decreases the eective area of the exhaust nozzle; a valve assembly which controls the flow of fluid from the iiuid source to the actuator, said valve assembly having a solenoid operated valve element which, when in a first position, produces movement of the actuator in the said one direction and which, when in a second position, produces movement of the actuator in the said opposite direction; a throttle for the propulsion unit; a two position switch; a cam which moves with the throttle and which causes the switch to move from its first contact position to its second contact position when the throttle is positioned for maximum power without afterburner; an emergency power source; a first electrical circuit which includes the emergency power source and the first contact position of the Switch and which energizes the solenoid -operated valve element moving it into its said first position; a second electrical circuit which includes the emergency power source and the second contact position of the switch and which energizes the solenoid operated valve element moving it into its said second position; and means dependent upon the instantaneous altitude of the unit for deenergizing the second electrical circuit when the area of the exhaust nozzle has reached to a predetermined maximum amount.

2. Emergency control apparatus for the variable exhaust nozzle of a jet propulsion unit said apparatus comprising a pressurized fluid source; a uid operated actuator which, when moved in one direction, increases the effective area of the exhaust nozzle and which, when moved in the opposite direction, decreases the effective area of the exhaust nozzle; a valve assembly which controls the flow of fluid lfrom the fiuid source to the actuator, said valve assembly having a solenoid operated valve element which, when in a first position, produces movement of the actuator in the said one direction and which, when in a second position, produces movement of the actuator in the said opposite direction; a throttle for the propulsion unit; a two position switch; a cam which moves with the throttle and which causes the two position switch to move from its first contact position to its second contact position when the throttle is positioned for maximum power; an emergency power source; a stepped cam; a three position switch, said stepped cam, said three position switch and said variable exhaust nozzle being operatively coupled one to another such that the three position switch occupies its first position when the area of the nozzle is less than a predetermined range of values and occupies its second position when the nozzle area falls within said predetermined range of values and occupies its third position when the area of the nozzle exceeds said predetermined range of values; a barometric switch which closes at a predetermined altitude; a first electrical circuit which includes the emergency power source and the first Contact position of the two position switch and which energizes the solenoid operated valve element moving it into its said first position; a second electrical circuit which includes the emergency power source and the second contact position of the two position Aswitch and the first position 'of the three position switch and which energizes the solenoid operated valve element moving it into its said second position; and a third electrical circuit which includes the emergency power circuit, the second contact position of the two position switch, the second contact position of the 'three position switch, and the barometric switch, said third electrical circuit being adapted to energize the solenoid operated valve element and move it into its said second position.

References Cited in the file of this patent UNITED STATES PATENTS 1,056,194 Martineau Malz 18, '1913 2,551,372 Haltenberger May l, 1951 2,619,794 Lombard Dec. 2, 1952 2,623,352 Sedille et al. Dec. 30, 1952 2,683,348 Petry July 13, 1954 

